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T2*-weighted image (TE=4.9 ms) for a stage IV HNSCC patient (Pt No: 5). Marker lines represent image positions used in the assessment of motion correction. B: Time traces of nodal (LN) and primary (P) projections without (S(t)) and with motion correction (S(t)MOCO). Pronounced global motion (i.e. swallowing) is marked with an asterisk. Persistent motion artifacts present in the primary tumor are indicated with an arrow.

Scatter plots comparing individual MRI measurements (tumor volume, baseline R2* and percentage of fluctuating volume) against pathology (Hoechst 33342 uptake for perfusion, pimonidazole adduct formation for hypoxia) determined from the cohort of CALR xenografts.

Fluctuating volume percentages detected for HNSCC metastatic lymph node ROIs between two MR sessions 48 hours apart (solid lines - responders, dashed lines - non responders).

Examples of Ktrans and R2* distributions for fluctuating and non-fluctuating parts of human HNSCC (Patient No 5, N2). The non-enhancing part of the tumor (Ktrans = 0) is indicated with an asterisk.

Supplementary Figure Captions

Examples of R2* time series (left column, R2* range 40 s-1) and corresponding power frequency spectra (R2* power range displayed: 0 - 30) for voxels within human HNSCC classified as significantly fluctuating (tumor - top two rows) and without significant fluctuations (tumor - middle two rows, adjacent muscle - bottom row).

Example of coronal T2-weighted image of two simultaneously scanned mice bearing CALR HNSCC xenografts (mice IV and V, tumors are marked with arrows) and a phantom containing 1.5 mM gadoterate meglumine (Dotarem, Guerbet, Villepinte, France) in saline, acquired using the asymmetric high-resolution three element receive coil.

Examples of R2* time series (left column, R2* range 40 s-1) and corresponding power frequency spectra (R2* power range displayed: 0 - 30) for voxels within CALR HNSCC xenografts classified as significantly fluctuating (CALR tumor - top two rows) and without significant fluctuations (CALR tumor - middle two rows, adjacent muscle - bottom row).

PURPOSE: To investigate the combined use of hyperoxia-induced ?R(2) * and ?R(1) as a noninvasive imaging biomarker of tumor hypoxia. MATERIALS AND METHODS: MRI was performed on rat GH3 prolactinomas (n = 6) and human PC3 prostate xenografts (n = 6) propagated in nude mice. multiple gradient echo and inversion recovery truefisp images were acquired from identical transverse slices to quantify tumor R(2) * and R(1) before and during carbogen (95% O(2) /5% CO(2) ) challenge, and correlates of ?R(2) * and ?R(1) assessed. RESULTS: Mean baseline R(2) * and R(1) were 119 � 7 s(-1) and 0.6 � 0.03 s(-1) for GH3 prolactinomas and 77 � 12 s(-1) and 0.7 � 0.02 s(-1) for PC3 xenografts, respectively. During carbogen breathing, mean ?R(2) * and ?R(1) were -20 � 8 s(-1) and 0.08 � 0.03 s(-1) for GH3 and -0.5 � 1 s(-1) and 0.2 � 0.08 s(-1) for the PC3 tumors, respectively. A pronounced relationship between ?R(2) * and ?R(1) was revealed. CONCLUSION: Considering the blood oxygen-hemoglobin dissociation curve, fast R(2) * suggested that GH3 prolactinomas were more hypoxic at baseline, and their carbogen response dominated by increased hemoglobin oxygenation, evidenced by highly negative ?R(2) *. PC3 tumors were less hypoxic at baseline, and their response to carbogen dominated by increased dissolved oxygen, evidenced by highly positive ?R(1) . Because the two biomarkers are sensitive to different oxygenation ranges, the combination of ?R(2) * and ?R(1) may better characterize tumor hypoxia than each alone. J. Magn. Reson. Imaging 2013;. � 2013 Wiley Periodicals, Inc.

The aim of this study was to use the combined carbogen-ultrasmall superparamagnetic iron oxide (CUSPIO) magnetic resonance imaging (MRI) method, which uses spatial correlations in independent susceptibility imaging biomarkers, to investigate and compare the impact of tumor size and anatomical site on vascular structure and function in vivo. Mice bearing either subcutaneous or orthotopic PC3 LN3 prostate tumors were imaged at 7 T, using a multi-gradient echo sequence to quantify R2∗, before and during carbogen (95% O2/5% CO2) breathing, and subsequently following intravenous administration of USPIO particles. Carbogen and USPIO-induced changes in R2∗ were used to inform on hemodynamic vasculature and fractional blood volume (%), respectively. The CUSPIO imaging data were also segmented to identify and assess five categories of R2∗ response. Small and large subcutaneous and orthotopic tumor cohorts all exhibited significantly (P

The recently described combined carbogen USPIO (CUSPIO) magnetic resonance imaging (MRI) method uses spatial correlations in independent imaging biomarkers to assess specific components of tumor vascular structure and function. Our study aimed to evaluate CUSPIO biomarkers for the assessment of tumor response to antiangiogenic therapy. CUSPIO imaging was performed in subcutaneous rat C6 gliomas before and 2 days after treatment with the potent VEGF-signaling inhibitor cediranib (n = 12), or vehicle (n = 12). Histological validation of Hoechst 33342 uptake (perfusion), smooth muscle actin staining (maturation), pimonidazole adduct formation (hypoxia) and necrosis were sought. Following treatment, there was a significant decrease in fractional blood volume (-43%, p < 0.01) and a significant increase in hemodynamic vascular functionality (treatment alteredδ R 2* carbogen from 1.2 to -0.2 s -1, p < 0.05). CUSPIO imaging revealed an overall significant decrease in plasma perfusion (-27%, p < 0.05) following cediranib treatment, that was associated with selective effects on immature blood vessels. The CUSPIO responses were associated with a significant 15% reduction in Hoechst 33342 uptake (p < 0.05), but no significant difference in vascular maturation or necrosis. Additionally, treatment with cediranib resulted in a significant 40% increase in tumor hypoxia (p < 0.05). The CUSPIO imaging method provides novel and more specific biomarkers of tumor vessel maturity and vascular hemodynamics, and their response to VEGF-signaling inhibition, compared to current MR imaging biomarkers utilized in the clinic. Such biomarkers may prove effective in longitudinally monitoring tumor vascular remodeling and/or evasive resistance in response to antiangiogenic therapy. © 2011 UICC.

Background: To assess antivascular effects, and evaluate clinically translatable magnetic resonance imaging (MRI) biomarkers of tumour response in vivo, following treatment with vanucizumab, a bispecific human antibody against angiopoietin-2 (Ang-2) and vascular endothelial growth factor-A (VEGF-A). Methods: Colo205 colon cancer xenografts were imaged before and 5 days after treatment with a single 10 mg kg−1 dose of either vanucizumab, bevacizumab (anti-human VEGF-A), LC06 (anti-murine/human Ang-2) or omalizumab (anti-human IgE control). Volumetric response was assessed using T2-weighted MRI, and diffusion-weighted, dynamic contrast-enhanced (DCE) and susceptibility contrast MRI used to quantify tumour water diffusivity (apparent diffusion coefficient (ADC), × 106 mm2 s−1), vascular perfusion/permeability (Ktrans, min−1) and fractional blood volume (fBV, %) respectively. Pathological correlates were sought, and preliminary gene expression profiling performed. Results: Treatment with vanucizumab, bevacizumab or LC06 induced a significant (P

Vessel size index (Rv, μm) has been proposed as a quantitative magnetic resonance imaging (MRI) derived imaging biomarker in oncology, for the non-invasive assessment of tumour blood vessel architecture and vascular targeted therapies. Appropriate pre-clinical evaluation of Rv in animal tumour models will improve the interpretation and guide the introduction of the biomarker into clinical studies. The objective of this study was to compare Rv measured in vivo with vessel size measurements from high-resolution X-ray computed tomography (μCT) of vascular corrosion casts measured post mortem from the same tumours, with and without vascular targeted therapy. MRI measurements were first acquired from subcutaneous SW1222 colorectal xenografts in mice following treatment with 0 (n = 6), 30 (n = 6) or 200 mg/kg (n = 3) of the vascular disrupting agent ZD6126. The mice were then immediately infused with a low viscosity resin and, following polymerisation and maceration of surrounding tissues, the resulting tumour vascular casts were dissected and subsequently imaged using an optimised μCT imaging approach. Vessel diameters were not measurable by μCT in the 200 mg/kg group as the high dose of ZD6126 precluded delivery of the resin to the tumour vascular bed. The mean Rv for the three treatment groups was 24, 23 and 23.5 μm respectively; the corresponding μCT measurements from corrosion casts from the 0 and 30 mg/kg cohorts were 25 and 28 μm. The strong association between the in vivo MRI and post mortem μCT values supports the use of Rv as an imaging biomarker in clinical trials of investigational vascular targeted therapies., Highlights ► Non-invasive quantitation of vessel calibre in tumour xenografts in vivo ► Assessment of tumour vessel calibre response to a vascular disrupting agent ► Generation of vascular corrosion casts from the same tumours imaged by MRI ► Quantitation of vessel calibre from corrosion casts by microCT ► Excellent agreement between the in vivo MRI and post mortem microCT vessel calibres

A combined carbogen ultrasmall superparamagnetic iron oxide (USPIO) imaging protocol was developed and applied in vivo in two murine colorectal tumor xenograft models, HCT116 and SW1222, with established disparate vascular morphology, to investigate whether additional information could be extracted from the combination of two susceptibility MRI biomarkers. Tumors were imaged before and during carbogen breathing and subsequently following intravenous administration of USPIO particles. A novel segmentation method was applied to the image data, from which six categories of R(2)* response were identified, and compared with histological analysis of the vasculature. In particular, a strong association between a negative ?R(2)*(carbogen) followed by positive ?R(2)*(USPIO) with the uptake of the perfusion marker Hoechst 33342 was determined. Regions of tumor tissue where there was a significant ?R(2)*(carbogen) but no significant ?R(2)*(USPIO) were also identified, suggesting these regions became temporally isolated from the vascular supply during the experimental timecourse. These areas correlated with regions of tumor tissue where there was CD31 staining but no Hoechst 33342 uptake. Significantly, different combined carbogen USPIO responses were determined between the two tumor models. Combining ?R(2)*(carbogen) and ?R(2)*(USPIO) with a novel segmentation scheme can facilitate the interpretation of susceptibility contrast MRI data and enable a deeper interrogation of tumor vascular function and architecture.

Item does not contain fulltext PURPOSE: To evaluate and histologically qualify carbogen-induced DeltaR2 as a noninvasive magnetic resonance imaging biomarker of improved tumor oxygenation using a double 2-nitroimidazole hypoxia marker approach. METHODS AND MATERIALS: Multigradient echo images were acquired from mice bearing GH3 prolactinomas, preadministered with the hypoxia marker CCI-103F, to quantify tumor R2 during air breathing. With the mouse remaining positioned within the magnet bore, the gas supply was switched to carbogen (95% O2, 5% CO2), during which a second hypoxia marker, pimonidazole, was administered via an intraperitoneal line, and an additional set of identical multigradient echo images acquired to quantify any changes in tumor R2. Hypoxic fraction was quantified histologically using immunofluorescence detection of CCI-103F and pimonidazole adduct formation from the same whole tumor section. Carbogen-induced changes in tumor pO2 were further validated using the Oxylite fiberoptic probe. RESULTS: Carbogen challenge significantly reduced mean tumor R2 from 116 +/- 13 s(-1) to 97 +/- 9 s(-1) (P

To evaluate noninvasive and clinically translatable magnetic resonance (MR) imaging biomarkers of therapeutic response in the TH-MYCN transgenic mouse model of aggressive, MYCN-amplified neuroblastoma.All experiments were performed in accordance with the local ethical review panel and the UK Home Office Animals Scientific Procedures Act 1986 and with the UK National Cancer Research Institute guidelines for the welfare of animals in cancer research. Multiparametric MR imaging was performed of abdominal tumors found in the TH-MYCN model. T2-weighted MR imaging, quantitation of native relaxation times T1 and T2, the relaxation rate R2*, and dynamic contrast-enhanced MR imaging were used to monitor tumor response to cyclophosphamide (25 mg/kg), the vascular disrupting agent ZD6126 (200 mg/kg), or the antiangiogenic agent cediranib (6 mg/kg, daily). Any significant changes in the measured parameters, and in the magnitude of the changes after treatment between treated and control cohorts, were identified by using Student two-tailed paired and unpaired t test, respectively, with a 5% level of significance.Treatment with cyclophosphamide or cediranib induced a 54% or 20% reduction in tumor volume at 48 hours, respectively (P.005 and P.005, respectively; P.005 and P.005 versus control, respectively). Treatment with ZD6126 induced a 45% reduction in mean tumor volume 24 hours after treatment (P.005; P.005 versus control). The antitumor activity of cyclophosphamide, cediranib, and ZD6126 was consistently associated with a decrease in tumor T1 (P.005, P.005, and P.005, respectively; P.005, P.005, and P.005 versus control, respectively) and with a correlation between therapy-induced changes in native T1 and changes in tumor volume (r = 0.56; P.005). Tumor response to cediranib was also associated with a decrease in the dynamic contrast-enhanced MR imaging-derived volume transfer constant (P = .07; P.05 versus control) and enhancing fraction (P.05; P.01 versus control), and an increase in R2* (P.005; P.05 versus control).The T1 relaxation time is a robust noninvasive imaging biomarker of response to therapy in tumors in TH-MYCN mice, which emulate high-risk neuroblastoma in children. T1 measurements can be readily implemented on clinical MR systems and should be investigated in translational clinical trials of new targeted therapies for pediatric neuroblastoma.http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12120128/-/DC1.

Background: Hypoxia-inducible factor-1 (HIF-1) mediates the transcriptional response to hypoxic stress, promoting tumour progression and survival. This study investigated the acute effects of the small-molecule HIF-pathway inhibitor NSC-134754. Methods: Human PC-3LN5 prostate cancer cells were treated with NSC-134754 for 24 h in hypoxia. Orthotopic prostate tumour-bearing mice were treated with a single dose of NSC-134754 for 6, 24 or 48 h. Treatment response was measured using magnetic resonance spectroscopy and imaging. Ex-vivo histological validation of imaging findings was also sought. Results: In vitro, NSC-134754 significantly reduced lactate production and glucose uptake (P

Overexpression of EGFR has been identified as a negative prognostic factor in squamous cell carcinoma of the head and neck (SCCHN). Patients with SCCHN who respond to EGFR-targeted tyrosine kinase inhibitors (TKIs) eventually develop acquired resistance. Colocalization of EGFR expression and tumor hypoxia in SCCHN is associated with poor outcome, suggesting a role for hypoxia in drug resistance. Non-invasive imaging strategies to accurately identify and monitor patients whose tumors have become resistant to EGFR-TKI therapy would have clinical value. As part of a pre-clinical multiparametric imaging study, we have investigated EGFR-TKI resistance using intrinsic susceptibility magnetic resonance imaging (IS-MRI), which relies on the dependence of the MRI transverse relaxation rate R2* on the ratio of oxy- to deoxyhemoglobin in blood. Given its relationship to blood oxygen saturation and pO2 in and around blood vessels, R2* and hyperoxia-induced ΔR2* are being investigated as imaging biomarkers of tumor oxygenation. IS-MRI was performed on size-matched xenografts derived from the EGFR TKI sensitive SCCHN cell line CAL27 and an isogenic subline resistant to multiple TKIs (gefitinib, erlotinib, and afatinib). Tumor-bearing mice were administered the hypoxia marker pimonidazole, and baseline R2* quantified from resistant (n=8) or sensitive (n=7) tumors whilst the host breathed air. Gas delivery was then switched to 100% O2, and tumour R2* measured again. Finally, mice were administered the perfusion marker Hoechst 33342. The extent of functional tumor vasculature and hypoxia were quantified ex vivo using fluorescence microscopy. Resistant tumors revealed regions of fast R2* (functional, deoxygenated vasculature) restricted primarily to the tumor periphery, while sensitive tumors exhibited a more heterogeneous distribution of fast R2* throughout. There was no significant difference in baseline R2* between the two cohorts (64 ± 4s-1 and 76 ± 5s-1, p=0.07). Hyperoxia resulted in a significantly smaller ΔR2* in the resistant tumors (-2.4 ± 1.4s-1) compared to sensitive tumors (-9.1 ± 2s-1, p Tumors with resistance to EGFR-TKIs exhibited a reduced hemodynamic MRI response that was associated with decreased vessel perfusion and increased tumor hypoxia. IS-MRI informs on phenotypic differences in tumor blood vessel distribution, functionality and oxygenation associated with EGFR-TKI resistance and sensitivity, affording useful non-invasive imaging biomarkers for investigating EGFR drug resistance and tumor hypoxia. Citation Format: Lauren CJ Baker, Carol Box, Arti Sikka, Gary Box, Suzanne A. Eccles, Simon P. Robinson. Evaluating imaging biomarkers of acquired resistance to targeted EGFR therapy in xenograft models of human squamous cell carcinoma of the head and neck (SCCHN). [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4459. doi:10.1158/1538-7445.AM2013-4459

Neuroblastoma (NBL) is the most common extracranial solid tumor of childhood, accounting for between 7-10% of paediatric cancers. The proto-oncogene MYCN is amplified in 25% of NBL and is associated with high-risk disease, enhanced tumor angiogenesis and poor survival. A genetically-engineered mouse model for high risk, MYCN-amplified NBL has been generated by directing expression of MYCN to the peripheral neural crest of transgenic mice. As part of a multi-parametric MRI study, we have evaluated the native spin-lattice relaxation time T1, sensitive to the ratio of bound to free water in tissue, as a potential noninvasive biomarker of treatment response of TH-MYCN NBL to three different classes of anti-cancer agent. TH-MYCN mice with abdominal tumors were identified by palpation and imaged prior to and following treatment. Native T1 (ms) was quantified at 7T using an inversion recovery (IR)-trueFISP sequence. In control cohorts, tumor progression over 48 hours and 4 days was associated with no significant change in T1. A single 25mg/kg dose of cylophosphamide, the current standard of care for childhood NBL, caused a significant 54% reduction of tumor volume at 48 hours. Treatment of TH-MYCN NBL with CPM leads to extensive cell death, which occurs primarily through apoptosis, and this response was associated with a highly significant 15% reduction in native T1. Given the hypervascular nature of NBL, their response to anti-vascular therapies was also investigated. Treatment with the pan VEGF receptor inhibitor cediranib (6mg/kg daily over 2 days) resulted in significant 19% anti-tumor activity and 8% reduction in T1 at 48 hours. Furthermore, this response was associated with a significant reduction in uptake of the perfusion marker Hoechst 33342 compared to control, but no difference in necrosis. Treatment with a single 200mg/kg dose of the colchicine derivative ZD6126 resulted in significant and unprecedented 43% anti-tumor activity at 24 hours, and which was also associated with a significant 14% reduction in native T1. Histology revealed a significant reduction in Hoechst 33342 uptake and extensive tumor necrosis. Collectively, these data show a systematic reduction of native T1 in the TH-MYCN model with successful chemotherapy. The CPM and ZD6126-induced reduction in T1 is consistent with a histologically confirmed reduction in cell density and increased extravascular space following cytotoxic therapy. The reduction of T1 following treatment with cediranib may be attributable to the resolution of edema caused by reduced vascular permeability. Accurate quantification of T1 affords a generic noninvasive biomarker for chemotherapy-mediated cell death in the TH-MYCN model. The high sensitivity of T1 will accelerate the pre-clinical evaluation of novel therapeutics for childhood neuroblastoma in this model. Quantitation of native T1 could be easily incorporated into conventional imaging protocols used in clinical trials. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 5290. doi:10.1158/1538-7445.AM2011-5290

The master regulator in hypoxic cell survival and adaptation is the hypoxia-inducible factor-1 (HIF-1) pathway. Altered HIF-1 regulated gene expression drives a tumour towards a more malignant phenotype. HIF-1 is thus a therapeutic target, and small molecule inhibitors such as NSC-134754 are being investigated. Glucose transporter 1 (GLUT-1) is an important downstream target of the HIF-1 pathway, with fundamental roles in intracellular glucose flux and availability. Given the intrinsic role of GLUT-1 in glucose metabolism, the ability of NSC-134754 to evoke a unique metabolic response in vitro and in vivo was investigated. Human PC3LN5 prostate tumour cells were treated with 7.5µM NSC-134754 and incubated in a humidified hypoxic workstation (1.0% O2) for 24h. Western blot analysis demonstrated a reduction in GLUT-1 expression in treated cells compared to controls. GLUT-1 immunocytofluorescence confirmed control cells exhibited extensive membranous and diffuse cytoplasmic expression compared to treated cells. Culture media and cell extracts were collected and metabolites analysed using 1H magnetic resonance spectroscopy (MRS). A significant decrease in glucose consumption (p3 fold compared to control cells (p Mice bearing established (∼1cm diameter) orthotopic PC3LN5 prostate tumours were treated with either 100mg/kg i.p. NSC-134754 (n=4) or vehicle alone (n=5) for 24h. Subsequent semi-quantitative immunohistochemical analyses revealed a significant 28 ± 2% decrease in GLUT-1 membrane expression in the treated tumours compared to controls (p These data suggest that NSC-134754 has a profound effect on glucose metabolism in vitro and in vivo. Treatment of PC3LN5 cells for 24h in hypoxia significantly reduced the expression and distribution of GLUT-1, decreased glucose uptake and reduced lactate production. A reduction in glucose transport and lactate production have been shown to be indicators of response to therapy. The increased uptake and metabolism of glutamine/glutamate may reflect compensatory mechanisms for reduced glycolysis in order to sustain cellular bioenergetics. Interestingly, we have also shown that NSC-134754 increased intracellular glucose accumulation. Many glycolytic enzymes are known gene targets of HIF, thus a reduction in their availability (and hence glycolysis) could lead to glucose trapping. To our knowledge, this is a novel finding of a small molecule inhibitor of the HIF pathway. Increased intracellular glucose with decreased glucose uptake has been reported with other therapeutics in vitro. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4074. doi:10.1158/1538-7445.AM2011-4074

Solid tumors typically exhibit hypoxic regions which impact negatively on chemotherapy and radiotherapy. A key player in cellular adaptation to the hypoxic microenvironment is the transcription factor hypoxia inducible factor-1 (HIF-1) [1]. HIF-1 target genes mediate a wide range of actions promoting changes to cell metabolism, angiogenesis, proliferation, invasion and metastasis, hence HIF pathway inhibition represents an attractive therapeutic strategy. Recently, the small molecule HIF pathway inhibitor NSC-134754 was identified from an in vitro screen of the NCI Diversity Set [2]. In this study we have investigated the acute response of orthotopic PC3 prostate tumors to NSC-134754 in vivo using magnetic resonance imaging (MRI). Ex vivo histological markers of tumor hypoxia and perfusion were also obtained, in addition to tumor VEGF, a pro-angiogenic factor downstream of HIF-1. Orthotopic prostate tumors were propagated by injecting 1×105 PC3 cells into the ventral prostate gland of male NCr nude mice. Once tumors reached approximately 1cm in diameter mice were administered with 100mg/kg NSC-134754 i.p. and MRI was performed 6 or 24 hours later. An untreated control group was also included. Diffusion-weighted MRI was used to determine the tumor apparent diffusion coefficient (ADC), sensitive to tissue cellularity, and dynamic contrast-enhanced MRI data acquired to provide estimates of Ktrans (dependent on vascular permeability, blood flow and volume) and ve (the fraction of extravascular, extracellular volume). At study end, mice were administered pimonidazole and Hoechst 33342, enabling the degree of hypoxia and perfused (functional) vasculature to be subsequently quantified by immunohistochemistry and fluorescence microscopy. VEGF expression in tumor homogenates was assayed by ELISA. A significant increase in ADC was observed 24 hours post treatment with NSC-134754 (6.6 ± 0.3×10−4mm2/s, n=6) compared to treated tumors evaluated 6 hours after treatment (5.8 ± 0.2×10−4mm2/s, n=7, p The data suggest that ADC provides a non-invasive imaging biomarker of response 24 hours following treatment with NSC-134754 in orthotopic PC3 prostate tumors, is associated with an increase in tumor hypoxia and independent of any changes in tumor blood flow/vascular permeability. Histological analysis of cellular necrosis is currently being performed to provide qualification of the increased tumor ADC and evidence of anti-proliferative effects of NSC-134754. Citation Information: Mol Cancer Ther 2009;8(12 Suppl):C90.